Systemic lupus erythematosus (SLE) is a diverse, systemic autoimmune disease which causes significant morbidity and early mortality, especially in minority populations and in women of child-bearing age. By the time patients receive a SLE diagnosis, the majority have ongoing aggressive inflammatory processes and oftentimes damage that cannot be reversed. Understanding the basic mechanisms of disease initiation and perpetuation will provide necessary information for earlier diagnosis, prevention trial design and directed therapeutics for this complex disease. To accomplish these goals, we have assembled a number of preclinical autoimmune disease collections which will provide the critical infrastructure to accomplish our aims. These include serial pre-disease samples from individuals who develop SLE while in the US military, serial samples from blood relatives of lupus patients who do and do not transition to lupus, individuals with incomplete lupus who subsequently transition to SLE classification and autoantibody positive and autoantibody negative healthy controls. Preliminary data has identified initial humoral epitopes of several lupus autoantibody systems; these will be confirmed and explored as potential predictors of high-risk populations and potential toleragens. Autoantibody positive healthy individuals have unique serum cytokine and chemokine profiles, some of which are shared with SLE patients and others which are unique to healthy individuals with autoantibodies against RNA or DNA associated proteins. These subjects also have unique cellular responses to select cytokines and increased cellular activation profiles. Additionally, individuals who eventually transition to clinical SLE are found o have dysregulation of select cytokines and chemokines years before disease onset and hydroxychloroquine has been associated with a delayed onset of SLE classification and slowed autoantibody accrual. The following aims will build on these preliminary findings and will be used to address pivotal clinical questions of what predicts SLE development and identify mechanisms of preclinical autoimmunity that contribute to transition to clinical disease. These aims are to: 1) identify and confirm early humoral epitope targets for select lupus-associated specificities across a spectrum of pre-clinical lupus collections, 2) evaluate the role of IL1 receptor antagonist:IL1beta ratios and BLyS levels, as well as other peripheral cytokine or chemokine measurements, in the transition from preclinical autoimmunity to SLE disease classification, and 3) assess immune cell activation and regulatory pathways that are altered prior to clinical disease onset. These preclinical resources and our cumulative and evolving experience in this area will allow us to provide unique and necessary insights to the Autoimmune Disease Prevention Study Group, as well as to further develop targets for preclinical intervention in autoimmune disease prevention.